Silicone rubber compositions are used in a wide variety of applications because they form cured products featuring the favorable properties of weathering and heat resistance and excellent rubbery properties such as hardness and elongation.
In the semiconductor packaging art, polyphthalamide resins (PPA) and liquid crystal polymers (LCP), which are thermoplastic resins having excellent heat resistance, have recently been under study on their use as packaging materials. Lead frames and electrodes are generally made of metals including Ag, Au, Ni, Pd and the like, which are rather difficult to bond to resins. The soldering technology associated with packages using these materials has changed to lead-free high-temperature solders. Many troubles arise from high-temperature stress, thermal cycling, and hot humid storage, for example, separation readily occurs at the interface between packages and silicone resins.
For addition cure type silicone rubber compositions, it is a common practice to add silane coupling agents to improve adhesion. Since reaction does not proceed to the completion, these compositions allow separation to occur in a test under rigorous conditions. If intense reaction takes place, the compositions discolor or turn opaque and cannot be used in optical applications.
Reference should be made to JP-A 2003-174059 and JP-A 2002-338833.